Businesses across the United States, still grappling with the double-whammy of the coronavirus pandemic and the economic shutdown it caused, face a new challenge this winter: the return of flu season just as many in cold-weather climates retreat indoors.
Millions of employees work in buildings with mechanical heating, ventilation and air conditioning (HVAC) systems, which have a tremendous effect on indoor air quality. Daily, humans consume two pounds of food and four pounds of water — but 30 pounds of air. The quality of that air is critical.
How can businesses optimize their facilities to keep employees and customers safe? As business customers try to balance their energy use with HVAC best practices this season, they will look to their energy providers for guidance. That’s why it is important for energy utilities to keep business customers informed about ventilation benefits and requirements.
Achieving clean air
The most common cause of indoor air pollution is an accumulation of contaminants found inside buildings. These include automotive exhaust, biological organisms, building materials, cleaning agents, pesticides and more. Alone, or in combination, these pollutants may cause adverse health effects, including headaches, dry cough, eye irritation, dizziness and drowsiness. To ensure indoor air is free of harmful concentrations of pollutants, it’s essential to have a well-designed, well-maintained and operational ventilation system.
Due to the pandemic, building ventilation has received much more attention as a way to help people stay healthy. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) and the Centers for Disease Control and Prevention (CDC) have published guidelines for the operation of HVAC systems during the pandemic.
ASHRAE believes that transmission of COVID-19 through the air is sufficiently likely enough that airborne exposure to the virus should be controlled. Following these recommendations will increase energy consumption within the building, but the health and comfort of occupants is much more important in these times. Customers should use at least one of the cleaning techniques listed below:
- Operate under 100% outdoor air; disable demand-controlled ventilation (DCV)
- Run residential forced-air systems continuously on low-speed (fan on)
- Operate restroom exhaust 24/7
- Flush building air pre- and post-occupancy for periods of 2 hours each
- Avoid exhaust air re-entrainment as much as possible
- Maintain indoor relative humidity levels between 40% and 60%
- Use MERV-13 filters or higher with subsequent testing, adjusting and balancing (TAB)
- Use HEPA filters but recognize their higher pressure drop (consider stand-alone units)
- Use ultraviolet germicidal irradiation (UVGI) in the form of UV-C
- Implement sanitation using air ionizers or ozone generators (when people are not present)
- Sanitize using vaporized hydrogen peroxide (H2O2)
- Sanitize using photocatalytic oxidation (PCO) which combines UV irradiation with a catalyst material
Fighting germs with energy
The National Electric Manufacturers Association (NEMA), American Lighting Association (ALA) and Underwriters Laboratories (UL) recently published a position paper on UV-CC germicidal devices, which are rapidly entering the market.
The right wavelength and dose (mJ/cm2) of ultraviolet radiant energy can kill bacteria and inactivate viruses. The most effective ultraviolet wavelength is 200 to 280 nanometers (nm) known as invisible UV-C (far UV). The main points of this position paper include the following:
- While UV-C radiation is proven to have sanitizing and germicidal effects, the first proof of effectiveness against COVID-19 is only just emerging.
- UV-C overexposure can cause damage to the eyes and skin.
- Overexposure can occur in just seconds.
- Exposure severity depends on UV wavelength, intensity, proximity to the source and time of exposure.
- UV-C emission is invisible and does not cause us to blink or look away, magnifying the hazard.
- Some short wavelength UV-C germicidal devices can also generate ozone, which can damage our lungs.
- Many consumer-oriented devices do not employ proper device containment (product enclosure) design such as covers and interlocks that prevent exposure.
- Product certification, not behavioral safeguards alone, is required to mitigate risks of personal injury from UV-C products.
- Certification only addresses device safety, not product effectiveness at sanitation.
UL deems portable UV sterilizers and personal UV wands as not safe for a home setting. Portable air cleaners with internal (contained) UV-C and UV-C sterilization boxes, cabinets or containers should be certified as meeting ANSI/IES RP-27 photobiological safety requirements. With certified devices, the UV-C source is inside the product enclosure and a safeguard disables the UV-C when an access door is opened.
Ventilation resources for business customers
In terms of ventilation energy consumption, fans driven by electric motors consume almost all the energy required for ventilation. Choosing a fan/drive combination with a Fan Energy Index (FEI) greater than 1.0 will maximize energy efficiency.
ASHRAE’s free Indoor Air Quality Guide is a great resource for achieving optimal ventilation in commercial buildings. ASHARE also provides a one-page Guidance for Residential Buildings with a link to 24 Frequently Asked Questions about residential ventilation.